(1) Field of the Invention
The present invention relates to a silver halide emulsion. More particularly, the present invention relates to a silver halide emulsion having a high sensitivity, particularly, high sensitivity to light of low illuminance.
(2) Prior Art
It is a universal demand in the field of silver halide photographic sensitive materials to obtain a photosensitive material having a high sensitivity. Various techniques have been proposed and patented already. One of these is a technique disclosed in U.S. Pat. No. 3,320,069 in which a thiocyanate is used in a step of forming emulsion grains. It is also disclosed in the specification of Japanese Patent Application No. 60-158891 (U.S. Ser. No. 886,052) that the control of IR absorbance at 2052 cm.sup.-1 of a thiocyanate in silver halide grains is important for photographic sensitivity, pressure resistance, etc. when the thiocyanate is used in the formation of the grains. However, sufficient sensitivity has yet to be obtained by these processes in particular sensitivity to light of a low illuminance has been unsatisfactory.